Finally, we have an explanation for one of the most bizarre celebrity moments of 2014: Justin Bieber‘s surprise appearance at the televised Fashion Rocks event in New York in September, where he stripped down to his Calvins on stage while leggy model Lara Stone looked on approvingly.

Most viewers probably thought the same thing: “Wow, the Bieb must have really good weed.”

Alas, while that is probably true, the reason for the unscripted striptease is a bit more pedestrian: he was paid to do it.

The Canadian singer was unveiled today as the new face and chiseled body of Calvin Klein‘s latest underwear and jeans campaign, accompanied by Stone who has been modeling CK lingerie for the past couple of seasons.

Here’s some of the imagery shot by Mert & Marcus, which you will likely see as many times as you’ve heard ‘Baby’.